The present invention relates to an improved multiple purpose instantaneous gas water heater, and particularly to an improved operation of such a heater, and to multiple uses for a gas water heater, such as a shower and the like.
2. Discussion of Prior Art
Previously, a variety of instantaneous gas water heaters were used. Among such water heaters are instantaneous gas water heaters having proportional gas operations; this type of water heater controls heat gain in response to controlled volume feeding of gas. Such a device, although often used, was not always satisfactory. Further, if could be used only for hot water supply, however, and such a device could not be satisfactorily used for multiple purposes, however.
In view of the disadvantages of such conventional devices, the present invention is directed to a multiple-purpose instantaneous gas water heater having a high capability for multiple uses, and is adapted to be responsive to the needs of consumers.
First, conventional devices in the form of proportional gas operated water heaters are limited in that they have only limited control, in the sense that they only control the volume of gas fed. Accordingly, once the volume of water being fed exceeds the highest limit of control for the volume of gas being fed, e.g., when the water pressure of the water being supplied source is higher than a predetermined value, it is quite difficult for the hot water temperature to reach a set up temperature (this would occur, for example, when a temperature drop in the water being fed is extremely severe, as occurs during the winter season). In fact, it is so unlikely that the temperature will reach such a set up temperature under these circumstances that a user had to throttle a source faucet by hand in order to control the volume of water being fed as a countermeasure, i.e., a user could only obtain a desired temperature of hot water by touching the water.
In order to resolve such a disadvantage, the inventor of the present invention previously offered such a device with the following improvement; this was designed for devices where the hot water temperature was virtually uncontrollable because it could only be controlled by the volume of gas used with respect to a set up temperature. In this device, an automatic valve was provided for throttling excess water flow greater than a limited range of water volume so that it would not enter a heat exchanger when within a set up temperature. This device is illustrated in U.S. Pat. No. 4,501,261.
In the type of water heater in which the feeding gas volume and feeding water volume are controlled a new method of controlling a burner has been introduced. That is, in view of the structure of conventional burners, previously the lowest limit of combustion was approximately 20% or 25% of the level of the highest limit of combustion, so that when the highest limit was increased, the lower limit also increased.